Remove insignificant trailing zeros from a number

Question

Have I missed a standard API call that removes trailing insignificant zeros from a number   Ex   var x   1 234000    to become 1 234  var y   1 234001     stays 1 234001   Number toFixed   and Number toPrecision   are not quite what I m looking for

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Pure regex answer  n replace      0-9   1-9  0     0      1      I wonder why no one gave one

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Here s a possible solution   var x   1 234000    to become 1 234  var y   1 234001     stays 1 234001  eval x  -- gt  1 234 eval y  -- gt  1 234001

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I needed to solve this problem too when Django was displaying Decimal type values in a text field  E g  when  1  was the value  It would show  1 00000000   If  1 23  was the value  it would show  1 23000000   In the case of a  decimal places  setting of 8   Using parseFloat was not an option for me since it is possible it does not return the exact same value  toFixed was not an option since I did not want to round anything  so I created a function   function removeTrailingZeros value        value   value toString           if not containing a dot  we do not need to do anything     if  value indexOf          -1            return value               as long as the last character is a 0 or a dot  remove it     while  value slice -1       0     value slice -1            amp  amp  value indexOf          -1            value   value substr 0  value length - 1             return value

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After reading all of the answers - and comments - I ended up with this   function isFloat n        let number    Number n      n  amp  amp  n   1     0    eval parseFloat n     n      return number      I know using eval can be harmful somehow but this helped me a lot   So   isFloat 1 234000            1 234  isFloat 1 234001            1 234001 isFloat 1 2340010000        1 234001   If you want to limit the decimal places  use toFixed   as others pointed out   let number    Number n      n  amp  amp  n   1     0    eval parseFloat n  toFixed 3     n    That s it

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None of these solutions worked for me for very small numbers   http   numeraljs com  solved this for me   parseFloat 0 00000001 toFixed 8       1e-8  numeral 0 00000001  format  0    00000000         0 00000001

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If you convert it to a string it will not display any trailing zeros  which aren t stored in the variable in the first place since it was created as a Number  not a String   var n   1 245000 var noZeroes   n toString       1 245

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I needed to remove any trailing zeros but keep at least 2 decimals  including any zeros  The numbers I m working with are 6 decimal number strings  generated by  toFixed 6     Expected Result   var numstra   12345 000010    should return 12345 00001 var numstrb   12345 100000    should return 12345 10 var numstrc   12345 000000    should return 12345 00 var numstrd   12345 123000    should return 12345 123   Solution   var numstr   12345 100000  while  numstr numstr length-1       0                    numstr   numstr slice 0  -1      if  numstr numstr length-1       0    break       if  numstr numstr length-3            break      console log numstr     12345 10   Logic   Run loop function if string last character is a zero  Remove the last character and update the string variable  If updated string last character is not a zero  end loop  If updated string third to last character is a floating point  end loop

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You can try this one to minify floating numbers  var n   0 0000  n   parseFloat n toString         output n   0      n   3 14000  -- gt  n   3 14

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If you cannot use Floats for any reason  like money-floats involved  and are already starting from a string representing a correct number  you could find this solution handy  It converts a string representing a number to a string representing number w out trailing zeroes   function removeTrailingZeroes  strAmount            remove all trailing zeroes in the decimal part     var strDecSepCd           decimal separator     var iDSPosition   strAmount indexOf  strDecSepCd       decimal separator positions     if   iDSPosition     -1             var strDecPart   strAmount substr  iDSPosition       including the decimal separator          var i   strDecPart length - 1          for     i  gt   0   i--                 if   strDecPart charAt i       0                     break                                   if   i    0                 return strAmount substring 0  iDSPosition             else                  return INTPART and DS   DECPART including the rightmost significant number             return strAmount substring 0  iDSPosition    strDecPart substring 0 i   1                        return strAmount

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I had a similar instance where I wanted to use  toFixed   where necessary  but I didn t want the padding when it wasn t   So I ended up using parseFloat in conjunction with toFixed   toFixed without padding  parseFloat n toFixed 4      Another option that does almost the same thing This answer may help your decision  Number n toFixed 4        toFixed will round pad the number to a specific length  but also convert it to a string  Converting that back to a numeric type will not only make the number safer to use arithmetically  but also automatically drop any trailing 0 s   For example   var n    1 234000       n   parseFloat n       n is 1 234 and in number form   Because even if you define a number with trailing zeros they re dropped   var n   1 23000      n    1 23

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I had the basically the same requirement  and found that there is no built-in mechanism for this functionality     In addition to trimming the trailing zeros  I also had the need to round off and format the output for the user s current locale  i e  123 456 789    All of my work on this has been included as prettyFloat js  MIT Licensed  on GitHub   https   github com dperish prettyFloat js    Usage Examples   prettyFloat 1 111001  3      1 111  prettyFloat 1 111001  4      1 111  prettyFloat 1 1111001  5      1 1111  prettyFloat 1234 5678  2      1234 57  prettyFloat 1234 5678  2  true      1 234 57   en-us        Updated - August  2018    All modern browsers now support the ECMAScript Internationalization API  which provides language sensitive string comparison  number formatting  and date and time formatting     let formatters         default  new Intl NumberFormat        currency  new Intl NumberFormat  en-US     style   currency   currency   USD   minimumFractionDigits  0  maximumFractionDigits  0         whole  new Intl NumberFormat  en-US     style   decimal   minimumFractionDigits  0  maximumFractionDigits  0         oneDecimal  new Intl NumberFormat  en-US     style   decimal   minimumFractionDigits  1  maximumFractionDigits  1         twoDecimal  new Intl NumberFormat  en-US     style   decimal   minimumFractionDigits  2  maximumFractionDigits  2        formatters twoDecimal format 1234 5678       result   1 234 57  formatters currency format 28761232 291      result    28 761 232    For older browsers  you can use this polyfill   https   cdn polyfill io v2 polyfill min js features Intl  locale en

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The toFixed method will do the appropriate rounding if necessary  It will also add trailing zeroes  which is not always ideal    4 55555  toFixed 2     - gt   4 56    4  toFixed 2     - gt   4 00    If you cast the return value to a number  those trailing zeroes will be dropped  This is a simpler approach than doing your own rounding or truncation math     4 55555  toFixed 2     - gt  4 56    4  toFixed 2     - gt  4

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If you use toFixed n  where n  gt  0  a more simple and stable  no more float operations  solution can be    n  toFixed 2  replace     0  0               0   gt  0    0 1234   gt  0 12    0 1001   gt  0 1     1   gt  1    1 1234   gt  1 12    1 1001   gt  1 1     100   gt  100    100 1234   gt  100 12    100 1001   gt  100 1   PS  if you use toFixed 0   then no replace is needed

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If we have some s string representation of a number  which we can get for example using the  toFixed digits  method of Number  or by any other means   then for removal of insignificant trailing zeros from the s string we can use  s replace     0     lt         0                                                  Results for various values of s                                             quot 0 quot    gt  0     quot 0 000 quot    gt  0         quot 10 quot    gt  10     quot 100 quot    gt  100         quot 0 100 quot    gt  0 1     quot 0 010 quot    gt  0 01         quot 1 101 quot    gt  1 101     quot 1 100 quot    gt  1 1     quot 1 100010 quot    gt  1 10001         quot 100 11 quot    gt  100 11     quot 100 10 quot    gt  100 1       Regular expression used above in the replace   is explained below   In the first place please pay the attention to the   operator inside the regular expression  which stands for  quot OR quot   so  the replace   method will remove from s two possible kinds of substring  matched either by the    0    part OR by the     lt         0    part  The    0    part of regex matches a dot symbol followed by all the zeros and nothing else till to the end of the s  This might be for example 0 0   0 is matched  amp  removed   1 0   0 is matched  amp  removed   0 000   000 is matched  amp  removed  or any similar string with all the zeros after the dot  so  all the trailing zeros and the dot itself will be removed if this part of regex will match  The     lt         0    part matches only the trailing zeros  which are located after a dot symbol followed by any number of any symbol before start of the consecutive trailing zeros   This might be for example 0 100  trailing 00 is matched  amp  removed   0 010  last 0 is matched  amp  removed  note that 0 01 part do NOT get matched at all thanks to the  quot Positive Lookbehind Assertion quot   i e     lt           which is in front of 0  in this part of regex   1 100010  last 0 is matched  amp  removed   etc  If neither of the two parts of expression will match  nothing gets removed  This might be for example 100 or 100 11  etc  So  if an input does not have any trailing zeros then it stays unchanged   Some more examples using  toFixed digits  Literal value  quot 1000 1010 quot  is used in the examples below  but we can assume variables instead   let digits   0     Get  digits  from somewhere  for example  user input  some sort of config  etc      quot 1000 1010 quot   toFixed digits  replace     0     lt         0              Result   1000      quot 1000 1010 quot   toFixed digits   1  replace     0     lt         0              Result   1000 1       quot 1000 1010 quot   toFixed digits   2  replace     0     lt         0              Result   1000 1       quot 1000 1010 quot   toFixed digits   3  replace     0     lt         0              Result   1000 101       quot 1000 1010 quot   toFixed digits   4  replace     0     lt         0              Result   1000 101       quot 1000 1010 quot   toFixed digits   5  replace     0     lt         0              Result   1000 101      quot 1000 1010 quot   toFixed digits   10  replace     0     lt         0              Result   1000 101    To play around with the above regular expression used in replace   we can visit  https   regex101 com r owj9fz 1

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I first used a combination of matti-lyra and gary s answers   r   n  toFixed 4  replace    0          Results    1234870 98762341   1234870 9876  1230009100   1230009100  0 0012234   0 0012  0 1200234   0 12  0 000001231   0  0 10001   0 1000   asdf    NaN   so no runtime error    The somewhat problematic case is 0 10001  I ended up using this longer version       r     n  toFixed 4       if  r match                r   r replace     0                   1234870 98762341   1234870 9876  1230009100   1230009100  0 0012234   0 0012  0 1200234   0 12  0 000001231   0  0 10001   0 1   asdf    NaN   so no runtime error    Update  And this is Gary s newer version  see comments    r   n  toFixed 4  replace    0-9      0-9   1-9        0       1     This gives the same results as above

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How about just multiplying by one like this   var x   1 234000 1     becomes 1 234  var y   1 234001 1     stays as 1 234001

[javascript] Remove insignificant trailing zeros from a number?

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